Barely has the freedom of information act come into force, than ministers have decided they want to stop journalists benefiting from it. Reporters, they claim, are overloading the system simply by making use of it.

A firm of consultants employed by Lord Falconer, the constitutional affairs secretary, has pronounced that FOI is costing Whitehall £24m a year, requires 400 civil servants to administer it, and takes up ministers' valuable time with too many "very high cost cases" brought by "serial requesters" - aka journalists. These figures have been used to back up a drastic plan to cap the number of requests from media organisations.

A cabinet paper leaked in July showed what Falconer was up to. In a bid to throttle the FOI infant in its cradle, he decided many requests would in future be rejected as too expensive to process. To head off critics, he would commission a cost-benefit analysis. This would then give him a "solid evidence base" to make the changes. The consultants, Frontier Economics were paid £75,000 to come up with the figures. The firm's directors include Sir Andrew Turnbull, the former Cabinet secretary - although Frontier Economics says he was not directly involved in the report.

Journalists fingered

The Frontier Economics report asserted that much of the £24m a year was spent on "serial requesters" from five groups - journalists, MPs, campaigners, researchers and private individuals. Journalists were explicitly fingered as being responsible for almost £4m of that total.

The most requests were being submitted, it was said, by the BBC, the Guardian, Evening Standard, Mail on Sunday and Sunday Times. This was the first piece of unreality. Frontier Economics estimated requests from each organisation by extrapolating from one week. The consultants estimate that the Guardian submits 500 to 700 requests a year to Whitehall departments. We estimate the actual figure is closer to around 250.

The consultants then apparently demonstrated that heavy expense comes when ministers are consulted on whether a piece of information should be released. In the small print, it transpired they had costed the time spent by ministers and private office officials at a notional £300 an hour - a figure that bears no relationship to their true salaries. When challenged, Michael Ridge, a Frontier director, said: "It is difficult to identify an appropriate benchmark for the cost of ministerial time. However the opportunity costs of ministerial time could be considered similar to that of senior executives or partners in a city law firm."

Ordinary civil servants' time was costed in the report at a more rational £25 an hour, based on their salaries. However, a buried footnote reveals that Frontier Economics arbitrarily increased its time estimates. Since officials also conversed with other officials, it doubled the estimates to take into account these other officials' time. Ridge said doubling these costs was "fair, if potentially conservative". Others might say that this was literally a case of "think of a number and double it".

And what about those 400 extra civil servants, notionally groaning under the burden of FOI? When the act was passed, it was said that no extra civil servants would be employed to run it. Indeed, Frontier Economics does not have any figures for extra hirings. The constitutional affairs department only points to 125 Whitehall staff who are employed to deal with FOI requests. Many of those have previously been engaged on answering letters from the public, or dealing with data protection requests. FOI has merely become another part of their existing job.

Already, Falconer's figures start to look somewhat fanciful. But even if that notional £24m was really being spent, it is minuscule compared with the hundreds of millions splashed out on press officers and advertising campaigns to tell the public about all the good work being done by ministers. The number of Whitehall press and public relations officers has trebled under this government to an awesome 3,200 people. This dwarfs the trivial amounts of time and money spent on administering FOI.

So what is really going on? Some ministers seem to loathe the idea of the public finding out what they are up to. Tony Blair's 1997 government was committed to passing the FOI act, but politicians then spent three years watering down the original scheme. When it eventually became law in 2000, Blair personally took the decision to delay its implementation for five years.

Finally, on January 1 2005, the public could begin submit FOI requests. But ministers quickly returned to conspiring against them. Falconer's two specific proposals, although apparently parsimonious, are aimed at stopping the most skilled requesters getting hold of politically embarrassing documents.

Currently, requests are free if the cost of locating and retrieving the information is less than a notional cap - £ 600 for Whitehall departments. But Lord Falconer now wants to add another factor which can be calculated against this cost - the time spent considering whether the information should be released. This is open to abuse because the more politically controversial the material, the more time ministers will spend worrying about the reaction to its disclosure.

A second proposed change is thoroughly outlandish. Requests over a three-month period from one media organisation, no matter how large, to a government department would be combined. By "aggregating" these requests the cost cap would soon be breached, allowing the department to reject them as "too expensive".

So if a BBC reporter at Radio Wiltshire sent a request to the education department, and the department considered it a time-consuming request for a lot of contentious information, it could refuse requests from anyone in the BBC for the next three months, whether from a different BBC radio station, Panorama or the 10 O'Clock News.

A government serious about changing the culture of secrecy would ditch these brazen proposals and instead tackle the real problems - departments that do not answer requests at all, delay their replies for months or obstruct disclosure by citing innumerable spurious reasons for secrecy. But that is a different story.